The present invention relates to apparatus for counting the number of stacked articles such as sheets of paper or related sheet materials and is more specifically directed to counting corrugated paper sheets.
Corrugated paper sheets are formed on conventional corrugating machines. Such sheets are sometimes deformed or buckled. Therefore, it is necessary that such a means of counting corrugated sheets be constructed in a manner to be able to apply sufficient pressure as to flatten out deformed sheets. Also, such an operation must be performed in a relatively short period of time as not to delay a high rate production line.
In the prior art, mechanical sheet counters are known for measuring the height of a stack and using that height to provide an indication of the number of sheets in the stack by dividing the stack height by a known sheet thickness. An example of such prior art is U.S. Pat. No. 3,298,605 of Bucke et al, which patent discloses an electro-mechanical device for counting the number of newspapers in a stack by indicating deviations from a normal stack number. The Bucke et al apparatus comprises a frame which straddles a newspaper conveyor carrying thereby a stack of newspapers. The frame supports a vertically rectilinearly movable ram for movement into contact with the top of the stack of newspapers. The ram carries a plurality of contact elements adapted to contact a corresponding set of stationary contact elements as mounted upon a plate. When a particular stationary contact is contacted by a ram contact, a corresponding light is energized indicating a specific ram height and a corresponding deviation from the normal number of newspapers. The height and number of newspapers in a normal stack are selectively varied by the switching mechanism.
The prior art stack counting apparatus is particularly adapted to count a single stack at a time and is not particularly adapted to effect the counting operation in an automatic fashion. In an aspect of the subject invention, it is desired to count not only the sheets of a single stack, but also to count the number of stacked articles as the stacks thereof are brought to the counting apparatus, keeping a running total of the sheets of the series of stacks. It is also desired to achieve a high degree of accuracy wherein an element in the form of a platen is moved and its movement is measured with a high degree of accuracy so that the stack height may be determined with a corresponding high degree of accuracy.